The Midtown Manhattan Restudy is a twenty-year follow-up investigation of a general population cohort of 695 adults originally studied in 1954. The total interview time spent with each cohort respondent in both years averaged over five hours. The central effort is a search of the 1954 baseline data for predictors of 1974 mental and somatic health and other life outcomes, taking into account selected facets of pre-1954 personal history and major post-1954 life events. Data analysis is under way and the first publication of findings will appear in the lead article of the December 1975 issue of the Journal of Health and Social Behavior. There reported is one of the first comparisons of mental health changes in a large panel of people after a twenty-year span of the adult life cycle.